[build] [bug] Fix building on macOS 10.14 failed (#5332)

* Fix building on macOS 10.14 failed

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

taichi/runtime/llvm/llvm_offline_cache.cpp

@@ -2,16 +2,6 @@
 
 #include <queue>
 
-#if __has_include(<filesystem>)
-#include <filesystem>
-namespace fs = std::filesystem;
-#elif __has_include(<experimental/filesystem>)
-#include <experimental/filesystem>
-namespace fs = std::experimental::filesystem;
-#else
-error "Missing the <filesystem> header."
-#endif  //  __has_include(<filesystem>)
-
 #include "llvm/AsmParser/Parser.h"
 #include "llvm/Bitcode/BitcodeReader.h"
 #include "llvm/Bitcode/BitcodeWriter.h"
@@ -39,16 +29,12 @@ static bool is_current_llvm_cache_version(
 }
 
 static std::string get_llvm_cache_metadata_file_path(const std::string &dir) {
-  std::stringstream tcb_ss;
-  tcb_ss << dir << "/" << kMetadataFilename << ".tcb";
-  return tcb_ss.str();
+  return taichi::join_path(dir, std::string(kMetadataFilename) + ".tcb");
 }
 
 static std::string get_llvm_cache_metadata_json_file_path(
     const std::string &dir) {
-  std::stringstream tcb_ss;
-  tcb_ss << dir << "/" << kMetadataFilename << ".json";
-  return tcb_ss.str();
+  return taichi::join_path(dir, std::string(kMetadataFilename) + ".json");
 }
 
 static std::vector<std::string> get_possible_llvm_cache_filename_by_key(
@@ -123,7 +109,7 @@ bool LlvmOfflineCacheFileReader::get_kernel_cache(
 
   auto &kernel_data = itr->second;
   if (kernel_data.owned_module == nullptr) {
-    const std::string filename_prefix = path_ + "/" + key;
+    const std::string filename_prefix = taichi::join_path(path_, key);
     kernel_data.owned_module = load_module(filename_prefix, key, llvm_ctx);
     TI_ASSERT(kernel_data.owned_module != nullptr);
     kernel_data.module = kernel_data.owned_module.get();
@@ -165,9 +151,7 @@ void LlvmOfflineCacheFileWriter::dump(const std::string &path,
 
   for (auto &[k, v] : data_.kernels) {
     std::size_t size = 0;  // bytes
-    std::stringstream filename_ss;
-    filename_ss << path << "/" << k;
-    std::string filename_prefix = filename_ss.str();
+    std::string filename_prefix = taichi::join_path(path, k);
 
     auto write_llvm_module =
         [&filename_prefix](
@@ -281,14 +265,13 @@ void LlvmOfflineCacheFileWriter::clean_cache(const std::string &path,
 
   if ((policy & CleanOldVersion) &&
       !is_current_llvm_cache_version(cache_data.version)) {
-    if (bool ok = fs::remove(get_llvm_cache_metadata_file_path(path)) &&
-                  fs::remove(get_llvm_cache_metadata_json_file_path(path));
+    if (bool ok = taichi::remove(get_llvm_cache_metadata_file_path(path)) &&
+                  taichi::remove(get_llvm_cache_metadata_json_file_path(path));
         ok) {
-      auto root_path = fs::path(path);
       for (const auto &[k, v] : cache_data.kernels) {
         const auto files = get_possible_llvm_cache_filename_by_key(k);
         for (const auto &f : files) {
-          fs::remove(root_path / f);
+          taichi::remove(taichi::join_path(path, f));
         }
       }
     }
@@ -328,17 +311,16 @@ void LlvmOfflineCacheFileWriter::clean_cache(const std::string &path,
         q.push(std::move(v));
     }
     TI_ASSERT(q.size() <= cnt);
-    auto root_path = fs::path(path);
     while (!q.empty()) {
       for (const auto &f :
            get_possible_llvm_cache_filename_by_key(q.top().kernel_key)) {
-        fs::remove(root_path / f);
+        taichi::remove(taichi::join_path(path, f));
       }
       q.pop();
     }
     if (cnt == cache_data.kernels.size()) {  // Removed all
-      fs::remove(get_llvm_cache_metadata_file_path(path));
-      fs::remove(get_llvm_cache_metadata_json_file_path(path));
+      taichi::remove(get_llvm_cache_metadata_file_path(path));
+      taichi::remove(get_llvm_cache_metadata_json_file_path(path));
     }
   }
 }

taichi/util/io.h

@@ -30,6 +30,21 @@ inline void create_directories(const std::string &dir) {
 #endif
 }
 
+template <typename First, typename... Path>
+inline std::string join_path(First &&path, Path &&...others) {
+  if constexpr (sizeof...(others) == 0) {
+    return std::string(path);
+  } else {
+    return std::string(path) + "/" +
+           taichi::join_path(std::forward<Path>(others)...);
+  }
+  return "";
+}
+
+inline bool remove(const std::string &path) {
+  return std::remove(path.c_str()) == 0;
+}
+
 template <typename T>
 void write_to_disk(const T &dat, std::string fn) {
   FILE *f = fopen(fn.c_str(), "wb");

tests/cpp/llvm/llvm_offline_cache_test.cpp

@@ -13,7 +13,7 @@ namespace fs = std::filesystem;
 #include <experimental/filesystem>
 namespace fs = std::experimental::filesystem;
 #else
-error "Missing the <filesystem> header."
+#error "Missing the <filesystem> header."
 #endif  //  __has_include(<filesystem>)
 
 #include "llvm/IR/IRBuilder.h"